1. Field of the Invention
The present invention relates to a clip for coupling an inner shield with the frame of a cathode ray tube.
2. Description of the Prior Arts
A cathode ray tube, and particularly a shadow mask type cathode ray tube is provided with a frame for installing a shadow mask, and the frame is for attaching not only the shadow mask but also an inner shield for shielding the influence of the geomagnetic field.
It is impossible to form the frame and the inner shield integrally due to their structural natures, and therefore, they are separately manufactured, the coupling of them being performed in the assembling process. A clip is required for coupling the frame and the inner shield in the assembling process, and has to satisfy the following three conditions. First, the clip should provide sufficient coupling so as to prevent the inner shield from oscillating or vibrating when external forces are applied to the shield; second, the clip should be easily manufactured; and third, the clip should be easily worked on when installed, i.e., an easy coupling of the inner shield with the frame.
As shown in FIG. 1, a conventional clip includes an elasticity providing portion A having self elasticity and formed in a V shape; a pair of shoulders S symmetrically extended outwardly in opposite directions at an angle from the elasticity providing portion A; and a pair of handles B each extended from a respective one of the shoulders S at an angle. An inner shield I is assembled with a frame F, overlying the frame F. Securing holes H are aligned with the frame F. The clips are inserted through the securing holes in such a manner that the frame and the inner shield are coupled between the elasticity providing portions A and the shoulders S.
Examples of such conventional clips are described in Japanese Patent Application Laid-open No. Sho 55-154041 and Japanese Patent Publication No. Sho 62-13787.
FIG. 2 shows a clip described in Japanese Patent Application Laid-open No. Sho 55-154041. In this device, a mask frame 26 for retaining a shadow mask (not shown) and a magnetic shield 27 for shielding from external magnetic fields are fixedly coupled by inserting elastic supporting members of a clip 20 into a hole 28 in the mask frame 26 and the magnetic shield 27. The elastic supporting members of the clip 20 have two portions formed in a V shape and extending outwardly at an angle of a juncture. The supporting member comprises a depressed portion 21 at the middle of each portion in an inwardly projected manner; a leading end portion 25 being outwardly extended to a pair of bent portions 22 having a V shape with an acute angle; and rear end portions 24 being inwardly extended toward the leading end portion 25 to a pair of bent portions 23 which bent portions 23 extend outwardly from the depressed portions 21. Such a clip is used in a color picture tube.
FIG. 3 shows a clip, described in Japanese Patent Application Laid-open No. Sho 62-13787. Such a clip is used in a shadow mask type color picture tube. A clip 30 has a V shape, and comprises a bent portion 31 and a pair of neck portions 32. The neck portions 32 are engaged in a hole 38 of a support frame 35 and a shielding member 36. First shoulder portions 33 are formed in the front of the neck portions 32, i.e., between the bent portion 31 and the neck portions 32, and second shoulder portions 34 are formed in the rear of the neck portions opposite the first shoulder portions 33. The width of the second shoulder portion 34 is larger than that of the first shoulder portion 33.
The above two examples of the prior art focused on only two of the three conditions mentioned above; they focused on whether the clip provides sufficient coupling and whether the clip is easily manufactured. The workability of the clip was disregarded.
The clips of the above examples have a gentle V shape, and are manually installed into the insertion holes. However, since the portion of the clip grasped by the worker, i.e., two free or leading end portions of the V shaped clip are sloped (i.e., inclined at an angle with respect to the surface of the frame), the clips tend to be slipped away from the hands of the worker and to be sprung off therefrom due to the elasticity of the clip, thereby causing low productivity and loss of the clips.